Electrical snap action switches of the general type with which we are concerned here are already known in the art, examples being described in U.S. Pat. Nos. 2,700,079; 2,854,540 and 4,283,609, as well as in German patent Nos. DE 23 56 024; DE 24 11 426 and DE 27 40 902 and others.
A typical switch of this type includes a longitudinal spring-like moving contact arm having a shorter part in tension longitudinally of the arm opposed by a longer part in compression longitudinally of the arm so that the longer arm part will be bowed or arched out of the plane of the shorter arm part. One end of the arm is mounted to a base. The opposite free end of the arm carries a moving contact. Mounted to the base is a fixed contact which extends opposite the moving contact at the free end of the arm. The switch also includes an actuator which presses against the contact arm so as to move the longer arm part transversely through the plane of the shorter arm part in opposite directions so that the free end of the arm snaps or flips between a closed position wherein the moving contact on the arm resiliently engages the fixed contact and an open position wherein the moving contact is spaced from the fixed contact.
Invariably, the fixed and moving contacts of the prior snap action switches of this general type are made separately and require separate assembly to the switch base or other support, giving rise to alignment problems and increasing the overall cost of such switches. Also, as electrical circuits become smaller and smaller, it becomes more and more difficult to fabricate and fix the different switch parts with the accuracy and high tolerances required to produce such very small switches in quantity on a reliable basis. Moreover, in some applications, a number of such switches must be positioned in a very small space on a printed circuit board or the like, creating a problem of packing the switches together as closely as possible in an array, while still maintaining good electrical and mechanical isolation between adjacent switches in the array.
The snap action switches available heretofore as typified by the ones disclosed in the aforementioned patents do not lend themselves to such miniaturization as would make them suitable for use in such applications where small size, low cost and reliability are all required in a single switch or switch array.